Stories

Deer in the garden

Probably one of the first things that comes to mind when any homeowner in suburbia thinks about "wildlife" in their vicinity are the deer they see occasionally browsing their garden, perhaps choosing between a scrumptious tulip or a more mundane shrub. Well, that or dodging them on the parkway on their way home late at night or early in the morning. Deer, specifically white tail deer, constitute the main "mega fauna" of suburbia in the vast majority of the United States (moose and elk making occasional visits to backyards in the most Northern states and Rocky Mountain West).

Deer can and are described in many ways; beautiful, graceful, skittish, prolific, pests, and a nuisance. Pretty much the whole gamut. They are probably all of these things to some degree. The deer along the Sligo Creek corridor in Maryland are certainly beautiful and occasionally a nuisance. It's their fecundity that perhaps first set me to thinking about the incredible resilience of nature in and around our cities, but perhaps particularly in the webs of greenery represented by the riverine parks and preserves that cut through so much suburban sprawl.

Nature can and clearly does scratch out an existence in-between the blacktop and manicured lawns of suburbia (and even more urbanized areas). How much of an existence? Of what quality? The answers are as varied as the multitude of miniature and unique ecosystems that form there. It is true that Sligo Creek itself presents a success story, but it also demonstrates the limitations of rehabilitation in a suburban area. When Sligo's water quality was studied in the 1990s and early 2000s, the results showed conditions to be dire.

Here in the DMV there is both reason for wonder, hope, and concern as we enter the third decade of this century. There have been and continue to be many projects seeking to restore and maintain healthy habitats that promote the biodiversity of native species in the region. It is tempting to believe that most of the challenges have been met. But appearances are often deceiving. Storm events, water main breaks, accidental or intentional discharge of pollutants into the streams pose serious challenges to the maintenance of a healthy ecosystems. Fortunately, nature is resilient, and with the proper care from her human allies, we may yet preserve much of her beauty and bounty for generations to come, even in the most unlikely of places.

Above: Rock Creek in the District of Columbia

Below: A heron fishing on Argyle Pond

The Liquid Heart

At the heart of the amazing diversity of flora and fauna found in the isles of green sprinkled between the car parks and over-manicured backyards of suburbia is always one essential element: water. Whether a simple brook, a rambling river or a humble ephemeral pond, water is life. The species that inhabit the wetlands and the waters themselves form the base in the pyramid of creatures that inhabit the suburban jungle.

For there to be "green" spots in the urbanized landscape there, of course, has to be plant life. Domesticated shrubs and flowers may provide forage for deer, but native species of flora are required for many of the animals and even insects that inhabit these spaces. Certain types of algae and aquatic plants are excellent for pond snails. Those snails in turn become food for the amphibians that are part of the diet of the foxes and birds of prey that frequent the ponds.

It all starts with water clean enough to support healthy plant life and the micro species that require both. The water that charges the streams and ponds generally comes from one of two sources, natural springs or rain. It is the latter where maintaining quality becomes complicated. While a vanishingly small fraction of rain may fall directly into a pond or stream, it is run-off from the rain that provides the bulk of the volume. And that is, of course, where problems begin. Run-off is generally hot and dirty in developed areas, disturbing or destroying the equilibrium needed for a healthy stream ecosystem.

While I discuss these issues elsewhere, what is amazing is nature's ability, when given a little help, to overcome these challenges. But this ability isn't unlimited. A stormwater retention pond near Sligo Creek is emblematic of both the potential and challenges of aquatic habitats in urban or suburban areas. Though officially unnamed, the pond I refer to in my thoughts as Argyle Pond is roughly the size of a basketball court in total surface area. fed by run-off from surrounding streets and built as part of the Sligo Creek restoration project with the dual purpose of preventing a rapid deluge from hitting Sligo and cleansing water of particulates before passing into the creek. From this seemingly inauspicious source, however, this humble pond has become a wellspring of life.

Argyle Pond is the home to a vast array of insects and micro-biotic life, tadpoles and frogs abound and fish of several species can be found at shocking sizes. From this base, the web of life extends up through the avian, reptilian and mammalian realms. Herons, Green, Yellow-crowned Night and Great Blue, have been consistent visitors, along with Belted Kingfishers and dozens species of songbirds including Kingbirds, gnatcatchers and warblers of various stripes. Geese and ducks nest on its banks while Wood Ducks nesting in nearby cavities visit it with regularity in Spring. Foxes hunt nearby for frogs or seek an easy omelet when Mother Goose leaves the nest.

Or at least this was the case. In the wake of the pandemic, patterns of human activity have been altered and with them the habit that supports so much life. Argyle Pond had always been surrounded by a defensive perimeter of inhospitable (to humans) and invasive bramble. Well-meaning persons removed much of the spiky undergrowth during the pandemic in an effort to "clean up" invasives. Laudable in principle, this effort could not have been more poorly timed. People discovered Argyle Pond during their exile from movie theaters and malls. Unfortunately, their interest in nature didn't include an appreciation for the delicate balance of the ecosystem into which they were about to step. And step they did. The banks around much of the pond have now been trampled, long grasses and bramble that once provided cover and forage were now removed or ground into a muddy barren. The downed trees that provided a respite and fishing platform for herons has become a jungle gym haunted at most hours by children of varying ages. Litter and contaminants have increased.

While wildlife is resilient and with time Argyle may recover some of its lustre as a magnet for its many species, it has ceased to be a spot at which you may find a micro-cosmic "Wild Kingdom" at almost any hour of the day. Finding a way to protect this resource as a resource primarily for wildlife, while still finding a way for humans to enjoy its beauty is a challenge to be met. Whether we can protect such oases of life in our human landscapes is something only time will tell.

The Constant Fisherman

Brrrrt! Brrrrt! A machine-gun like trilling cuts through the air up and down creeks and around ponds and lakes throughout the Eastern U.S. most of the year. That unique rat-a-tat-tat is the sound of the Belted Kingfisher making her presence known. Seemingly always on the move and definitely displeased with the dreaded presence of humans, Kingfishers are not easy birds to get to know. Around 12 inches long with a royal blue head and primaries, white breast and, in females, a red chevron or "belt" around their midsection, they are striking. They are also devoted to their craft and seem to hate any interference posed by meddling human eyes, erupting from their perches with an indignant "brrrt!" the moment they notice the interloper. For that reason they are somewhat hard to get to know, but worth the effort.

The Kingfisher diet consists, as one would expect, largely of smaller fish, but they are opportunistic and will eat frogs, tadpoles, aquatic insects, crawfish and even small birds or mammals. Their typical fishing technique involves a sharp plunge into the water with the beak being the instrument of capture, like herons, rather than talons like osprey or eagles. In fact, their feet, designed best for perching, are undersized for their bulk but make for a more effective streamline when folded for diving. While they will sometimes perform an "osprey hover" type technique before a dive, they typically like to watch a patch of water from an overhanging limb or perch and wait for prey to come to them.

They usually nest in ground cavities, and while not as much is known about their nesting habits as other species there are some interesting known details. They seem to prefer higher river or stream banks when they can find them. The hole entrance is circular with a drag mark at the center bottom caused by passage of their feet. Because they cannot digest their meals completely, their nest walls are often lined with the regurgitated bones of their prey. Occasionally they have been known to use tree cavities,

Kingfishers are found throughout the DMV, including in developed areas where the ecosystem is healthy enough to provide sufficient prey. Surveying the Sligo Creek watershed, one will find Kingfishers hunting at almost every retention pond and creek section containing fish. Given the lack of higher and sandier banks, it seems likely that many of these Kingfishers are nesting in old woodpecker nests.

Seeing so many Kingfishers in the area is a heartening sign that the ecosystem is functioning at a moderately decent level. Kingfishers are not an "apex" predator but are still closer to the top of the food chain in the small, wooded creek environments that are so common in the National Capital area. If they thrive its because flora, insects, amphibians and fish are thriving enough to sustain them. Hearing a Kingfisher's rattling call should put a smile on the conservationist's face.

The Beautiful Killers

Healthy ecosystems need balance. If certain species proliferate too much they can devastate the system, bringing ruin ultimately to all. White-tailed deer are a prime example of a species for whom the eradication of predators has lead to overpopulation to the detriment of the ecosystem. Smaller prey, however, generally have no such shortage of predators.

In the DMV tri-state, hawks, falcons, owls and eagles do the yeoman's work of checking the populations of rodents, snakes and amphibians. A number of raptor species make their home in this stretch of the greater Chesapeake Estuary, including Red-tailed hawks, Cooper's Hawks, Red-Shouldered Hawks, Peregrine Falcons, Bald Eagles, Barred Owls, Great Horned Owls and, occasionally, Snowy Owls, to name a few.

These species have overlapping territories and often compete for the same prey, bringing them at times into conflict amongst themselves. Great Horned Owls and Red-tails and Red-shouldered Hawks, for instance, have been well documented in attacking each other, usually with elimination of nestlings as the apparent object of the attack.

In general, however, the various species have specializations which tend to minimize their conflicts and allow them to concentrate on the serious business of hunting and raising young. Red-shouldered Hawks, like their smaller cousins the Sharp-shinned and Broad-winged, are smaller birds roughly the size of large crows that are well adapted to hunt in the crowded landscape of the lowland woods. They tend to specialize in small rodents, snakes and amphibians, usually diving from a perched position 15 to 25 feet from the ground. Red-tailed hawks, larger and broader of wing, have a similar diet but are more suited to gliding and swooping for a kill from a height above an open meadow or forest clearing.

Meanwhile, owls in general, unlike hawks, tend to be nocturnal or at least wait for dusk to begin their hunt. Some, like the Great Horned, are even less picky than hawks in their preference for habitat, fairing equally well across North America from open field and farmland to forested or swampy terrain. Others like the Barred tend to prefer wooded river bottoms.

Suburban and even urbanized areas are often host to these gorgeous predators. Many of these species make their home in the DMV. An abundance of prey, including the typical voles, field mice and frogs native to the Mid-Atlantic, as well as invasives like the Norway Rat, provides a stable supply of sustenance. The greater challenge is perhaps competition for nesting sites. While some raptors, perhaps most famously Peregrine Falcons, are found nesting on buildings and utility towers, finding prime nesting sites can be more of a challenge for other species.

Even Bald Eagles have been found nesting near lakes not far from the heart of Rockville, Maryland, county seat for over one million residents. Given appropriate food sources, nesting sites and lack of persecution, these majestic birds easily thrive near areas of human settlement. Outside suburbia, Bald Eagles are famous for their appearances at docks where fisherman tie off and in other propitious areas of human activity like Conowingo Dam.

Go with the (Slow) Flow

The movement for restoration of natural watercourses has gained momentum in the last 30 years thanks in large part to public projects, but also with increased interest of private land owners. Some impressive examples include Dixie Creek in Nevada, Long Creek in South Portland, Maine, the Coonamessett River in Massachusetts and Selah, Bamberger Ranch Preserve in Texas. The list is as varied in terms of climate, landscape and approach as it is extensive.

Dixie Creek is an example of a small but locally important stream found in a desert wilderness environment. Its degradation came about largely due to the unmindful grazing practices of ranchers over the last 100 years. Due to the destruction of the native flora which helped slow and broaden its course, the stream essentially had begun to run dry almost year around. The Bureau of Land Management directed its restoration to amazing effect over the last 10 years and it now serves as a literal oasis of green and source of water year round.

By contrast, Long Creek is an example of an urban/suburban watercourse that suffered from the common problem of run-off from impervious surfaces in the watershed. The jury is out on this project, but the problems faced are common ones. The plan calls for liberal use of retention ponds, hydrology management and a makeover of the riparian zone's flora by reintroduction of native species. The EPA's 2007 assessment of Long Creek showed that its loss of key species such as trout was due the altered flow caused by the increased amount of hard surface in the watershed, lack of "large woody debris" (an important factor in promoting invertebrate abundance) and increased water temperatures were the culprits.

Each of these examples fits within a specific environment with specific challenges. The goals and approaches taken by restoration projects have equally varied tools and goals for streams throughout the country, ranging from reintroduction of native fish species and improved landscape for the benefit of human activity, to the preservation of habitat for endangered or threatened species.

Two of the most common issues, perhaps particularly in more developed areas, are stream temperature and flow rate. The issue of toxic runoff or pollutants is more commonly understood and probably the first thing that most of us think of when we imagine threats to the health of any wetland or stream. But flow rate and temperature are equally critical to creating a healthy aquatic ecosystem. Long centuries of human "management" has seen a consistent trend towards straighter, harder and higher banked channels that are too fast, too turbid and too hot for many species.

To combat these problems, restoration efforts have employed several tactics. Commonly, and as is seen throughout the Washington metro area, including Sligo Creek, run-off is caught and filtered through rain gardens and retention ponds. This can actually create habitat for non-riverine species that can handle warmer water and are perhaps more tolerant of the types of pollutants caught in these pools. Some species can even filter certain types of toxins, improving the quality of the water. Where bank grades are reduced and native flora introduced, plant life can serve a similar function as well as providing food and shelter for a variety of insects, birds and other life.

Crossing the water's edge, there are a number of techniques known as "instream restoration" which can be used to slow flows and provide habitat enhancement. "Woody debris" - aka tree trunks - can be used to create pools and refuge for species especially when beneficial sediments are caught by the eddies created. Stone or wood can also be used to create plunge pools and "J-hooks" to protect banks without raising and hardening them.

For those who hope to see successful restoration in areas like suburban Washington, the challenge is to find ways to encourage restoration while finding acceptable compromises with human interests. All too often development around waterways has involved straightening the streams and clearing and flattening the land around them. With greater understanding and effort we can make or keep vital habitats like Rock and Sligo Creeks, Oxon and Holmes Run, and many others, areas where wildlife can thrive.

The Furry Engineer

A series of bubbles ripple across the water, disrupting what is an otherwise glassy-green pond surface under the shade of the dusk-lit forest. Gliding just below the water's surface is the continent's most formidable terraformer - the North American Beaver. A graceful swimmer despite her rubenesque shape, this dedicated mother is gently introducing her young ones to a new swimming hole that might just represent their new home. It's no exaggeration to say that one of the key resources that drew Europeans to the new continent was gold - furry gold. Finding precious little wealth in the form of precious metals in the Eastern half of the continent, colonists had to content themselves with two sources of quick wealth. The first was tobacco, which was good for the colonists' finances and ruinous for their health. The second was beaver pelts, also good for the colonists' accounts but even worse the the beavers' health.

As many as 60 million beavers may have roamed the continent when the Europeans began colonization. While their numbers have dwindled and they have disappeared from much of their range due to human persecution and habitat encroachment, the population has rebounded significantly from its all-time lows to between 6 and 12 million today.

Part of the rebound is due to human efforts to reintroduce beavers into the ecosystem to repair and revitalize the wetland and riparian environments that have been degraded and damaged by centuries of human activity. Their reintroduction has been a success in a number of areas of the parched US Mountain West, though there are still instances of conflict between human and beaver activity. In an era of increased sensitivity to the fragility of our forests, the felling of trees by beavers, along with the flooding caused by dam construction, can raise the call for beaver elimination even among the environmentally conscience.

Beavers do untold good for the environment, starting with the creation of wetlands which provide habitant for an incredible number of species. While a beaver pond does its own immediate good for its own denizens, from amphibians and fish to the mammals that stalk its banks, the general slowing of water flows tends to make the areas around the ponds retain vast amounts of additional water, allow for the conditions in which vital plant life can take hold and serves to encourage sediment deposition which effectively cleans the water that passes downstream. These areas are more resistant to fire damage and keep the course of the slowed streams flowing with life giving water throughout the seasons in areas where beds were known to go dry in the wake of human and cattle activities.

Beavers are being spotted at an increasing rate in the DMV, and have in the last decade even made some not-so-celebrated appearances on the National Mall. Many counties in the Mid-Atlantic have webpages dedicated to "living with beavers" and generally counsel a measured approach to "managing" them. It remains to be seen how well humans and beavers will be able to partner to improve the environment to the benefit of all. I have my money on the beavers' combination of cuteness and dogged perseverance making them an increasingly adorable "problem" in our suburban and exurban landscapes.

The Invasives

Darting in and out of the bushes of seemingly every lawn or intoning their tuneless "jeep jeep jeep" from a perch of a human-built structure, you are sure to find the most common bird in North America - the ubiquitous House Sparrow. The only problem is that this is not only a non-native species to the continent, but a harmful invasive that does its level best to out-compete beneficial natives such as Eastern Blue Birds and Swallows and does tremendous damage in the process.

Known also as the English Sparrow, this bird differs in several ways from the native species of sparrow but most significantly in that it prefers to nest in cavities. Often they seem to prefer cavities in human structures, such as eves, but they will take any nest site available and that, unlike native sparrows, brings them into conflict with insect-eating natives like the Blue Birds and Purple Martins. The outcome of these conflicts is usually a gruesome death for the native species, due perhaps to the difference in beak structure between the seed-cracking sparrow beak and the more delicate insect-picking beaks of the natives. Whenever someone decides to become a Bluebird "landlord" by installing nest boxes to attract them, they should also be aware that this activity comes with perils for the birds and responsibilities for the landlord.

Invasive species include the European Starling, various turtles, the infamous Northern Snakehead fish, Burmese Pythons, Asian Carp, Zebra Mussels, and a bevy of flora that not only displace native plant life but also have devastating consequences for a host of native species dependent on them for habit and food. The cost is literally in the billions in terms of both financial impacts and lives of native species. The Zebra Mussel, for example, introduced into Great Lakes region at least by the 1980s, has caused untold destruction of habitat, damaging recreational and commercial viability of certain lakes and even destroying things like marine motors in the process.

The cause of these "invasions" is always the same - human activity, often intentional. Both House Sparrows and Starlings were introduced into the United States in the 19th Century, a comparative blink of the eye in evolutionary-biological terms. And their sudden advent on this continent (and others) has been devastating to native birds and caused damage to human activities that few would credit unless told, ranking as the number one crop pest in New Zealand, for example. Naturally, human activities are often the unwitting cause of some invasive outbreaks, such as the introduction of the Norway Rat around much of the world by European explorers and traders throughout the last millennium. Perhaps no intentional introduction of an invasive has been as tragic and destructive as the Europeans' penchant for releasing pigs onto islands throughout the world to serve as future food for passing ships.

While some find the subject difficult if not outright verboten, the fact is that control and elimination of invasives is both legal and, in my opinion, an ethical imperative. But for human activity, these species would not be in contact with the ecosystems they have now entered. It is important too that we distinguish between the merely "non-native" and the invasive. Where a species of plant or animal threatens the extinction or near elimination of species native to an ecosystem, they are truly invasive and a threat to destabilizing the entire natural order. Elimination need not be cruel, but it should be effective. It's important to recall that these species have "home" ecosystems in which their kinds thrive. No one would argue that the pruning shears should be used only sparingly when deciding between a 1,000 year old oak and a Kudzu vine. So too must action to cull even the more charismatic invasives be unsentimentally decisive if we are to preserve ecosystems which have evolved over tens of thousands of years.